<html lang="en">
	<head>
		<meta charset="UTF-8">
		<meta http-equiv="X-UA-Compatible" content="IE=edge">
		<meta name="viewport" content="width=device-width, initial-scale=1.0">
		<title>Document</title>
	</head>
  <style>
    :root{
      --b:blue
    }
    .container{
      width: 100px;
      height: 100px;
      background-color: #ff66cc;
    }

    .red{
      --c: red;
      width: 50px;
      height: 50px;
      background-color: var(--b);
    }
  </style>
	<body>
		<script>
		</script>
    <div class="container">
      <div class="red"></div>
    </div>
	</body>
</html>
